The present invention relates generally to a partition insulator having a seating in at least one insulator holder.
As discussed in the description introduction of CH-PS No. 464,321, it is known that the inside pressure of an individual compartment (for example, of a pressurized gas-insulated, metal-cased, high-voltage switchgear having individual compartments which are divided in a gas-tight manner by partition walls), rises relatively rapidly if an undesired electric arc appears as a result of any kind of disturbance. In order to control such an increase in the inside pressure and to thereby make an explosion of the metal casing impossible, it is known to arrange partition walls made from insulators as partition insulators. The walls have a stability such that they explode in the case of a bursting strength of about one-third of that pressure at which the metal casing enclosing the partition insulators bursts.
When an undesired electric arc appears within an individual compartment, one or both of the partition insulators bordering on the individual compartment may first rupture, owing to the ensuing increase in inside pressure. In this way, the pressure increase can now only occur within the greater volume and a pressure relief occurs. The bursting of yet another partition wall can still occur, however, although the electric arc has stopped, due to the (slower) increase in pressure in the greater volume (due to the rupture of the abovementioned partition insulator).
It is further proposed to limit the area of damage according to CH-PS No. 464,321 by arranging the partition insulators at points located between certain groups of individual compartments, the partition insulators having approximately the same bursting strength as the metal casing. In this way, however, partition insulators having different bursting strengths are required.
Further, it is well known from DT-OS No. 2 210,626 how to construct an insulating pin for pressurized gas-insulated, metal-cased, high-voltage switch-gears. The insulating pin serves simultaneously as a partition element between sequentially located pressurized gas-filled individual compartments which receive components in such switchgears. The insulating pin is weakened (in cross-section) at one or several points so that the pin will burst at these points in the event of increased pressures. The bearing strength of the pin, however, is maintained. The production of such insulator pins, however, requires complex and therefore expensive casting molds.
The reason for the complexity and expense involved with the insulator pins lies mainly in the fact that the insulator pins have to be precisely weakened in cross section at one or several points such that the weak points do not react in an undesired manner too early (e.g. with only slightly increased pressures). In that event, the high-voltage switchgear would be placed unnecessarily out of operation. The weak points, furthermore, must not allow a greatly increased pressure because the desired protection of the high-voltage switchgear would therefore not be guaranteed. Such an insulator pin does not only include an inhomogeneity in structure (at each of the points) but can also be inhomogeneous in material because the points (provided with a decreased cross section) can be made of a different material than the rest of the pin. Such insulator pins feature a wide range of reaction.
The pins have a further disadvantage, however, since it is possible to damage the pin at the sensitive weak points during handling. Even if the abovementioned considerations with respect to the insulator pin are disregarded, use of insulator pins is undesirable since identical insulator pins may have differing stabilities.
The task which serves as a basis for the present invention is to guarantee in the most simple way a predetermined insulator rupture or burst behavior as a function of the size and direction of the external forces acting on the partition insulator. This behavior is most preferably provided in the case of a partition insulator of uniform construction arranged in at least one insulator holder, and with application of only one specific insulator type and size class.
The solution of the task is made with regard to a partition insulator having a constructional development essentially in accordance with the present invention.
With a partition insulator according to the present invention, even when using only one insulator type and size class (without change of the insulator), it is entirely possible to correspondingly predetermine, as desired, the insulator predetermined rupture or the insulator rupture or burst behavior. These behaviors may be predetermined by an arrangement of bearing points, bearings or intermediate bearings between the partition insulator and the insulator holder. Even a relatively simple shape change of either the flange of the insulator holder and/or the partition insulator flange by the arrangement of the bearing points or bearings on the edges of the flange of the insulator holder facing the insulator and/or of the edges of the flange of the partition insulator facing the insulator holder brings about in a simple manner a determination of the partition insulator predetermined rupture.
With partition insulators and insulator holders constructed in this way, (especially in the case of pressurized gas-insulated, high-voltage switchgears with distribution of the respective metal equipment casing into mutually gas-tight divided individual compartments with a varying admissible upper limiting pressure of the insulating gas), there results a first advantage that adjacent individual compartments can be divided by a single partition insulator which reacts direction-dependently to varying bursting strengths. This advantage will enable one to realize, in the most simple way, a pressure-oriented graduation of the individual compartments of the respective switchgear casing.
It is especially advantageous to provide the partition insulator with a particular insulator holder according to the present invention because it is thereby possible to have a further varied differentiation of the insulator predetermined rupture or burst behavior in the most simple manner without a change of the partition insulator. In comparison with a partition insulator which is only supported on an edge, considerably smaller bends and (in the case of a disk-shaped or a circular plate-shaped basic form), smaller radial and tangential stresses appear in the case of a partition insulator having a form-locking and/or power-locking arrangement (or gripping or fixed-gripping) in an insulator holder. In this way, in the case of one and the same partition insulator including an insulator holder, an extension of the range of the pressure load capacity (with regard to the insulator rupture or burst behavior) may be made depending on the seating of the partition insulator.
In the case of a preferred form of construction, the partition insulator is to be constructed with an insulator holder in order (if special dimensions of the insulator are disregarded) for its predetermined rupture behavior to be varied advantageously as a function of a bendable part of the partition insulator having a free diameter between the bearing points or bearings.
The assumption that the elastic behavior of the partition insulator is herewith essentially a function of the ratio of the insulator thickness with respect to the abovementioned respective free diameter and further a function of the other dimensions of cast fittings in the center of the insulator (not depicted or described here in detail) as well as of the actual insulator shape deviating from the disk or circular plate shape, is herewith assumed as without question and the slight deviations resulting therefrom are disregarded.
It is essentially advantageous to construct the partition insulator in order thereby to guarantee in the most simple manner an independent predetermined rupture or insulator rupture or burst behavior as a function of the direction and magnitude of the external force acting on the partition insulator (e.g. the gas pressure in the case of pressurized gas-insulated high-voltage switchgears).
In addition, it is advantageous to construct the partition insulator together with an insulator holder having an open slot between the insulator and holder in order to utilize, in the most simple manner for the partition insulator, at least the stress (or bending-oriented) advantages of an outside and inside free resting disk or circular plate. These advantages are realized in the case of one or several axial extensions of the free slot varying from the quantity or value 0 (that is, resulting from bearing points or bearings being located further from the middle or axis) in this most simple manner for the partition insulator.
Further advantages achieved with the present invention consist in the avoidance of a relatively great reaction distribution with respect to the insulator rupture or burst behavior whereby the reaction accuracy is achieved consistently with the present invention in a most simple manner. Above all, the advantages are achieved without worsening the properties of the partition as an insulator. In this way, no varying insulator stabilities (produced more particularly by insulator weak points and/or by utilization of differing insulator materials and which establish an easy damage capability of such insulators) necessarily result from the present invention. Even with respect to the manufacture, however, the subject of the present invention is quite advantageous since it can be cheaply produced by relatively simple casting molds.
As seen from both an overall and a specific standpoint, the present invention enables, above all, electrical arc protection to be both improvable and solution-oriented in a relatively simple manner with respect to metal-cased, high-voltage switchgears.